okay, so my truck is leaking diesel into the radiator and out the overflow. Someone told me it has an o-ring blew. how hard and how much should this cost to do? i had the parts quoted at $250 but for labor they wanted $1200. They said labor was so high because they would have to pull the head. Is this true or are they bs'ing me? Also, the truck has began to smoke white when you get on it really hard; i'm thinking it's injectors as the stocks one have close to 200,000 on them. Any other thought?